Also known as urticaria, hives are raised, itchy weals that appear on your skin. They can pop up anywhere on your body, vary from a few millimetres to the size of a hand, and may go away within a few hours or last for a few weeks.
Hives are a reaction to histamine, a chemical released by your body as part of the immune response.
They’re more common in children, women aged 30 to 60 and anyone who’s susceptible to allergies.
Hives are classed as either:
You may have:
Hives are usually harmless but sometimes they can be the first symptom of anaphylaxis, a potentially life-threatening allergic reaction. Other symptoms of anaphylaxis include:
Call 999 if you think you or someone else has anaphylaxis.
Hives will probably go within 48 hours. But see your GP if they’re:
Your GP will examine your rash and ask about other symptoms to help work out what’s causing it.
Tests are often not necessary but sometimes your GP may refer you to an allergy clinic.
You may be referred for the following tests:
The most common cause of hives is an allergy. Common allergy triggers for hives include:
Non-allergy triggers include:
Possible causes include:
You may find that these triggers make hives worse or come back:
You may not need any treatment because hives often clear up within a couple of days. In the meantime, it’s best if you avoid any triggers you know you have.
If you have chronic hives your doctor may also refer you to a dermatologist, a consultant specialising in skin conditions. They may suggest stronger antihistamines or other medicines to suppress your immune system, such as ciclosporin and omalizumab.